The present invention relates to a motor and a motor case for a fan which may be used, for example, as a blower for a vehicle air conditioner. More particularly, the invention relates to a casing arrangement which permits the motor to be made small and light in weight, with reduced noise.
A blower motor for a vehicle air conditioner is generally attached to the blower housing via a steel mounting bracket which supports the motor. This type of motor conventionally has various shortcomings, such as difficult assembly and high cost of an integrally molded plastic flange. Also, the steel mounting bracket used to hold the motor in place is not interchangeable with respect to different motor sizes.
Japanese Patent Application Laid-Open No. 2-75799, discloses an arrangement for reducing noise and weight in which a plastic motor cover with an integrally molded flange and an elastic body are used together in place of a separate supporting flange. However, in that apparatus, the motor is held in the motor cover by means of screws, which can result in the transmission of excessive vibrations from the motor to the case and also does not allow for small variations in the size or shape of the motor housing.
Stringent environmental regulations and requirements which have recently been imposed have increased the need for reduction of the noise and weight of vehicles, to the point where it is no longer possible to achieve fully both goals by conventional means. For example, in the above Japanese Patent Application Laid-Open No. 2-75799 the motor housing and end bracket consist of thin or bored plates and a deeply drawn motor housing, while Patent Application Laid-Open No. 2-87952 utilizes a motor housing having open ends and an end bracket having a large opening. Although these arrangements achieve a weight reduction, they also cause an increase in noise due to insufficient structural rigidity. Thus, the objectives of reducing both weight and noise have come into conflict.
An object of the present invention is therefore to provide a small motor which realizes both a weight reduction of the motor housing and bracket, and a noise reduction as well.